Organic Nutrients Induced Coupled C- and P-Cycling Enzyme Activities During Microbial Growth in Forest Soils

Loeppmann, Sebastian; Breidenbach, Andreas; Spielvogel, Sandra; Dippold, Michaela A.; Blagodatskaya, Evgenia

doi:10.3389/ffgc.2020.00100

Cited by 21 publications

(10 citation statements)

References 68 publications

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“…Position-specific 13 C label showed a much higher mean residence time of ribose compared to glucose in soils, indicating the reuse or preservation of intact ribose-derived cell components in SOM (Bore et al, 2019). The addition of biomass building blocks (yeast extract) compared to glucose alone actually increased the amount of active enzymes and microbial yield in a forest soil, but did not increase the averaged growth rates or mineralization of the soil (Loeppmann et al, 2020). In addition, fungi were shown to mobilize resources from Gram-negative necromass and distribute it within the microbial food web (Zheng et al, 2021).…”

Section: Microbial Resource Miningmentioning

confidence: 96%

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Kästner

Miltner

Thiele‐Bruhn

et al. 2021

Front. Environ. Sci.

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The organic matter of living plants is the precursor material of the organic matter stored in terrestrial soil ecosystems. Although a great deal of knowledge exists on the carbon turnover processes of plant material, some of the processes of soil organic matter (SOM) formation, in particular from microbial necromass, are still not fully understood. Recent research showed that a larger part of the original plant matter is converted into microbial biomass, while the remaining part in the soil is modified by extracellular enzymes of microbes. At the end of its life, microbial biomass contributes to the microbial molecular imprint of SOM as necromass with specific properties. Next to appropriate environmental conditions, heterotrophic microorganisms require energy-containing substrates with C, H, O, N, S, P, and many other elements for growth, which are provided by the plant material and the nutrients contained in SOM. As easily degradable substrates are often scarce resources in soil, we can hypothesize that microbes optimize their carbon and energy use. Presumably, microorganisms are able to mobilize biomass building blocks (mono and oligomers of fatty acids, amino acids, amino sugars, nucleotides) with the appropriate stoichiometry from microbial necromass in SOM. This is in contrast to mobilizing only nutrients and consuming energy for new synthesis from primary metabolites of the tricarboxylic acid cycle after complete degradation of the substrates. Microbial necromass is thus an important resource in SOM, and microbial mining of building blocks could be a life strategy contributing to priming effects and providing the resources for new microbial growth cycles. Due to the energy needs of microorganisms, we can conclude that the formation of SOM through microbial biomass depends on energy flux. However, specific details and the variability of microbial growth, carbon use and decay cycles in the soil are not yet fully understood and linked to other fields of soil science. Here, we summarize the current knowledge on microbial energy gain, carbon use, growth, decay, and necromass formation for relevant soil processes, e. g. the microbial carbon pump, C storage, and stabilization. We highlight the factors controlling microbial necromass contribution to SOM and the implications for soil carbon use efficiency (CUE) and we identify research needs for process-based SOM turnover modelling and for understanding the variability of these processes in various soil types under different climates.

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Section: Microbial Resource Miningmentioning

confidence: 96%

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Kästner

Miltner

Thiele‐Bruhn

et al. 2021

Front. Environ. Sci.

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“…This correlation might be explained by increased translocation of assimilates as a C source to soil microorganisms by mycorrhizal plants and a consequently decreased need for saprotrophic C supply by the enzymatic hydrolysis of polysaccharides [46]. The ß-glucosidase activity links the C cycling with P mobilization [47] and is affected by organic fertilization, similar to phosphatase activities (see Figure 3).…”

Section: Discussionmentioning

confidence: 97%

Impact of the Legume Catch Crop Serradella on Subsequent Growth and P Mobilization under Barley in Different Fertilization Treatments

et al. 2021

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Legume catch crops can enhance soil fertility and promote the N and P supply of the subsequent main crop, especially with low mineral fertilizer use. However, the specific impact of catch crops on arbuscular mycorrhiza formation of the following main crop is unknown. Therefore, the impact of serradella (Ornithopus sativus) vs. bare fallow was tested on mycorrhiza formation, potential soil enzyme activities and plant-available P under subsequently grown barley (Hordeum vulgare) and different fertilization treatments (P-unfertilized—P0; triple superphosphate—TSP; compost—COM; combined—COM + TSP) in a long-term field experiment in northeastern Germany. Catch cropping significantly increased mycorrhiza formation of barley up to 14% compared to bare fallow. The impact of serradella on mycorrhiza formation exceeded that of the fertilization treatment. Serradella led to increased phosphodiesterase activities and decreased ß-glucosidase activities in soil. Plant availability of P was not significantly affected by serradella. These findings provide initial evidence that even serradella as a non-host crop of mycorrhizal fungi can promote the mycorrhiza formation of the subsequent crop and P mobilization in soil. We conclude that the prolonged vegetation cover of arable soils by the use of catch crops can promote P mobilization and transfer from P pools to the following main crops.

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“…First, the growth rate calculations by qSIP were based on an incorrect assumption of steady state after glucose addition, neglecting that microorganisms are not in a steady state during growth. Second, the application of qSIP one week after substrate input is too late compared to exponential growth usually occurring within 20-48 h after soil activation with substrate (see e.g., Meisner et al, 2013;Loeppmann et al, 2020). Therefore, microbial growth rates determined 7 days after glucose addition mirror substrate-induced successional changes and substrate re-utilization rather than bacterial growth rates.…”

Section: Methodological Constraintsmentioning

confidence: 99%

Bridging Microbial Functional Traits With Localized Process Rates at Soil Interfaces

et al. 2021

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In this review, we introduce microbially-mediated soil processes, players, their functional traits, and their links to processes at biogeochemical interfaces [e.g., rhizosphere, detritusphere, (bio)-pores, and aggregate surfaces]. A conceptual view emphasizes the central role of the rhizosphere in interactions with other biogeochemical interfaces, considering biotic and abiotic dynamic drivers. We discuss the applicability of three groups of traits based on microbial physiology, activity state, and genomic functional traits to reflect microbial growth in soil. The sensitivity and credibility of modern molecular approaches to estimate microbial-specific growth rates require further development. A link between functional traits determined by physiological (e.g., respiration, biomarkers) and genomic (e.g., genome size, number of ribosomal gene copies per genome, expression of catabolic versus biosynthetic genes) approaches is strongly affected by environmental conditions such as carbon, nutrient availability, and ecosystem type. Therefore, we address the role of soil physico-chemical conditions and trophic interactions as drivers of microbially-mediated soil processes at relevant scales for process localization. The strengths and weaknesses of current approaches (destructive, non-destructive, and predictive) for assessing process localization and the corresponding estimates of process rates are linked to the challenges for modeling microbially-mediated processes in heterogeneous soil microhabitats. Finally, we introduce a conceptual self-regulatory mechanism based on the flexible structure of active microbial communities. Microbial taxa best suited to each successional stage of substrate decomposition become dominant and alter the community structure. The rates of decomposition of organic compounds, therefore, are dependent on the functional traits of dominant taxa and microbial strategies, which are selected and driven by the local environment.

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Organic Nutrients Induced Coupled C- and P-Cycling Enzyme Activities During Microbial Growth in Forest Soils

Cited by 21 publications

References 68 publications

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Impact of the Legume Catch Crop Serradella on Subsequent Growth and P Mobilization under Barley in Different Fertilization Treatments

Bridging Microbial Functional Traits With Localized Process Rates at Soil Interfaces

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